Circuits for generating electrical impulses



Aug. 21, 1951 E. c. WHITE 2,554,824

cmcurrs FOR GENERATING ELECTRICAL IMPULSES Filed Feb. 5. 1948 fnve'nfor: Eric Lawrefic. Casi/4 1 Whife Afforney paten ted Aug. 2 1, 1951 elect-testament; I

MPULSES Eric Lawrence'- Casling White: yen "England; as:

signer to Electric'& Musical IndustriesLimited; Hayes, England;- a company "of" Great Britain Appuaiicifrebriraiy s, leitlis Iir'Grea't Britain reiiroaryi, "1947" V GCIaimsl This invention relates to circuits for generat ing electrical impulses and has" for itsobject to provide an improved circuit capable of generating impulses of very stable duration. e

According to the invention'there is;provided-a circuit for generating electrical impulses com: prising a pair of electron discharge valves each having a cathode, control electrode and anode,- said devices being connected at their cathodes to n e t ica del l ne ndbei e-soccou edtha sa dci c t n ates lec i al im ulses wi ha duration determined substantially only by' the de= l y of said de 'lin -m. v. t In Order th t he i irwe tioh,.m ;.:be cl arly, nd s an re ly. ear dnto iect-itw l.

now' be more fully described with reference: to-

the accompanying drawings, inwhichg w W Figure 1 illustrates a circuit according tooneembodim ent of theinventiorl' and Figure 2 illustrates a circuitaccording toanother embodiment of theinvention t v Y I W Referring now to Figure 1,' I andfZ are valves each having a cathode, control electrode and anode. Resistances 3 and flare connected in the cathode circuits respectivelyof valves I and 2 and the d pff W VQ L LQ ELZ are coupled by a coupling circuit ,Gomprising resista e. 5 and delay network 6 whosce input'terini and 8 are connected in series'wit resistant 5? At the end'of'said delay.network reinotfirom said input terminals said delaynetwork i open circuited. Thus the terminals Sand l! l at the remote end of sai'd' networli' are left unconnected.

To cause said circuit to be capable of generating impulses, the anode circuit of valve I is provided with an anode load resistance II connected to the positive terminal of a source of anode current shown conventionally at I2 and the anode of valve l is coupled to the control electrode of valve 2 by coupling capacity I3. The control electrode of valve 2 is connected through resistance I4'to a point of suitable bias potential. The impulses generated by the circuit may be derived from the load resistance I5 connected to the anode of valve 2 and which is also connected to said source I2.

In one use of the circuit according to the invention regularly repeating controlling impulses of negative sense indicated at I6 may be applied to the control electrode of valve I so that an impulse is generated by the circuit only upon the incidence of a controlling impulse. The circuit is arranged so that in the intervals between the generated impulses valve I is conducting and valve 2 is non-conducting. Thus, upon the incidence of one of said controlling impulses the current in valve I isreduced and in consequence the'p'otentialat the anode of valve I is ln'creased.- This increase' of potential is communicated to the control I ele ctro deofvalve 2 through capacity I3 and valve 2' is rendered conducting. .Thus,'the" cathode potential of valve 2 is caused to rise, and, byyirtu'e 'ofthe coupling between the="c'ath-' ode's of' said valves; valvel is reri'derednonconducting. At the same time an impulsewhose amplitude may be suitablyprop'ortioned by corre'ctlyselebting thvalue' of resistance is caused to propagate along the delaynetwork G'Ttowards its remote end from which end said impulse. is reflected sd'as-to' cause valve. l to return to the conducting condition upon the 'incidenc'e of. the

reflected impulse back at' terminals 1 andZB. Whenvalve I is again rendered conducting, valve- 2"is caused to cease to conduct by-virtue of the coupling'betwe'en the' anode of valve I andTcon-' trol electrodeof valve2'andthe circuitreturns to its initial'condition' with valve I conducting andvalvez non conducting. v

In the arrangement thus described the time constant of the coupling circuit" comprisin cap'acity" I35 and resistance I4, said time constant being-I efiectiv'e :at the controli'electrode of valve 23- is made longer than theintervals betweensa'id controlling? impulses. If desired, "however; the: coupling betweenithe anodefic'ircuit" oflvalve" I andthe controlelectrode' f valve'2 may be such as to pass direct current. v.

Figure 2 of the drawings illustratesa further embodini'entofithe invention, the elements shown inf Figure 2 which correspond to"those 'shown' Figure 1 being given the same reference numerals. In this embodiment of the invention the oathode resistances 3 and 4 are omitted and the oathodes are connected together as shown and are connected to the input terminals 1 and 8 of the delay line 6. The delay line 6 thus presents at its input terminals I and 8 an impedance common to the cathode circuits of the valves I and 2. The terminals 9 and ID of the delay line B are effectively short-circuited. The control electrode of the valve I is biased by means of a resistance I7 connected to a suitable source of potential which is arranged so that the valve I is conducting and is rendered non-conducting on the application of a negative controlling impulse to the control electrode of the valve. When a negative controlling impulse is applied to the valve I the potential of the anode of the valve increases, this increase of potential being communicated to the control electrode of the valve 2 through the coupling capacity I3 so that the valve 2 which was previously non-conducting is rendered conducting. The cathode potential of the valve 2 is thus caused to rise and by virtue of the connection between the cathodes of the two valves, valve I is held non-conducting and at the same time an impulse is propagated along the delay line 6 and is reflected from the shortcircuited end of the delay line in inverted sense. When the reflected impulse reaches the terminals 'I and 8 the cathode of valve l is driven negatively so that the valve I is rendered conducting and valve 2 is then rendered non-conducting.

Thus the circuits may be used to generate pulses of a highly stable duration under the infiuence of controlling impulses the duration of which need not be highly stable nor the same as that of the generated impulses. Also the circuits may be employed in free-running manner, (i. e. no controlling impulses being applied), so as to generate pulses of highly stable duration and of period determined by the time constant of the coupling circuit associated with the control electrode of valve 2, said control electrode being properly biassed so that free-running oscillations are generated by the circuit. By biassing the control electrode of valve 2 sufiiciently negative one stable state may be imparted to the circuit so that, if desired, said circuit may be employed as a so-called flip-flop circuit generating a single impulse under the influence of a single applied impulse, the duration of the generated impulse being independent of the duration of the applied impulse.

I claim:

1. A circuit for generating electrical impulses, comprising a first and a second electron discharge valve each having a cathode, a control electrode and an output electrode, means .for connecting said output electrodes to a power supply, means coupling the output electrode of the first valve to. the control electrode of the second valve, means for periodically rendering the first valve nonconducting to render the second valve conducting while the first valve is nonconducting, a delay line connectedv to both of said cathodes, and means for feeding to said delay line impulses set up at the cathode of said second valve when the latter is rendered conducting, and means for feeding said impulses after traversing said delay line to the cathode of said first valve to render said valve conducting to control the duration of said generated impulses.

.2. A circuit for generating electrical impulses, comprising a first and a second electron discharge valve each having a cathode, a control electrode 4 and an output electrode, means for connecting said output electrodes to a power supply, means coupling the output electrode of the first valve to the control electrode of the second valve, an impedance in the cathode lead of each of said valves, means for periodically rendering the first valve nonconducting to render the second valve conducting while the first valve is nonconducting,

electrical impulses having a pair of input terminals with one terminal connected between one impedance and the cathode of one of said valves and the other connected between the other impedance and the cathode of the other of said valves, the end of said delay line remote from said input terminals being open-circuited, whereby when said second valve is rendered conducting a control impulse set up at said second cathode is propagated along said delay line and is applied to the cathode of the first valve to render it conducting.

3. A circuit for generating electrical impulses, comprising a first and a second electron discharge valve each having a cathode, a control electrode and an output electrode, means connecting said output electrodes to a power supply, means coupling the output electrode of the first valve to the control electrode of the second valve, means for periodically rendering the first valve nonconducting to render the second valve conducting while the first valve is nonconducting, a delay line for determining the duration of said electrical impulses, said delay line having a pair of input terminals with one terminal connected to the cathodes of said valves, whereby the delay line provides an impedance common to the cathode circuits of said valves, the end of said delay line remote from said input terminals being shortcircuited, whereby when said second valve is rendered conducting a control impulse set up at said second cathode is propagated along said delay line and applied to the cathode of the first valve to render it conducting.

' ERIC LAWRENCE CASLING WHITE.

REFERENCES CITED UNITED STATES PATENTS Name Date Jacobsen et a1, Mar. 2, 1948 Number 

